This invention relates to boring tools, and particularly to a fixture for holding and precisely aligning a replaceable cutter head and a boring bar for joinder together by silver soldering.
The boring bars and cutter heads are commonly supplied in a range of diameters, such as 3/8 inch, 1/2 inch, 5/8 inch, 3/4 inch and 1 inch. Each cutter head is formed with a pocket that receives a triangular cutting tool(insert) that can be rotatably adjusted to present different cutting edges to the work requiring machining. Each boring bar can be a circular cross-sectioned bar having a conical end adapted to fit into a conical socket in the cutter head; the conical surfaces are brazed together to join the bar to the head.
These boring bars and cutter heads are commercially available as separate units or as single units already assembled. One commercial source for such boring bars and cutter heads is the Kennemetal Corp. of Latrobe, Pa.
A problem arises when the customer attempts to braze a boring bar to a cutter head without the aid of a fixture to hold and accurately align the separate pieces during the brazing operation. The brazed assembly can be operationally deficient, due for example to the cutting edge of the tool (insert) being above or below the proper cutting position, or at an incorrect approach angle.
The present invention relates to a fixture that can be used by the customer to properly align the cutter head and boring bar during a brazing operation. The fixture is designed for ready use by a person who does not have precise knowledge of the geometry necessary to achieve accurate alignment of the bar and cutter head.
The fixture comprises a base having a laterally projecting seat element adapted to fit into the tool-reception pocket of a cutter head. A slidable retainer is mounted on the base to push the cutter head against the projecting seat element; the seat element and retainer cooperatively hold the cutter head in a precise position suitable for brazing to the associated boring bar. The boring bar is suspended above the cutter head by means of a clamp structure that is mounted on a vertical post extending upwardly from the base (which holds the cutter head).
The fixture is designed so that the user is not required to perform complex adjusting operations in order to accurately align the boring bar and cutter head. The fixture has non-adjustable reference surfaces thereon that are engagable with surfaces of the boring bar and cutter head to achieve a properly aligned assembly without special manual adjustments or measurements.
In order to adapt the fixture to use with various different diameter boring bars and cutter heads the fixture includes a common base and a series of different interchangeable triangular seating elements; each seating element has its own mounting block adapted to be releaseably secured to an upstanding side face of the base.
the invention provides a relatively low cost fixture that can be used to accurately align a cutter head and boring bar for brazing operations thereon. Interchangeable parts of the fixture permit the fixture to be used with a range of different diameter boring bars and cutter heads.